Optimization of mobilization regimes of blood hemopoietic stem cells in patients with multiple myeloma

AIM: To determine an optimal cyclophosphamide dose in the mobilization scheme providing adequate collection of CD34+ cells in patients with multiple myeloma (MM), to optimize the time of initiation of granulocytic colony-stimulating factor (G-CSF) administration, to study effects of induction therapy schemes on results of mobilization and collection of CD34+ cells. MATERIAL AND METHODS: Department of hemoblastoses chemotherapy and bone marrow transplantation of the Russian Hematological Center performed mobilization of autologous blood hemopoietic stem cells (BHSC) in 93 MM patients treated in 2001-2010. This was done with cyclophosphamide and G-CSF. The former was used in 59 cases in a dose 6 g/m2, in 34 cases - 4 g/m2. RESULTS: Myelotoxic agranulocytosis after cyclophosphamide administration developed in all the patients and was observed for 3-10 days (median 5 days). Agranulocytosis ran without documented infections in 51 (54.8%) patients, with febril fever - in 42 (45.2%) patients. Cepticemia, pneumonia, necrotic enteropathy, stomatitis, herpetic lesion of the skin were registered in 9, 4, 11, 14 and 6 cases, respectively. Severe thrombocytopenia (< 30 x 10(9)/l) occurred more frequently in administration of 6 g/m2 cyclophosphamide. It was corrected with 2-5 transfusions of thromboconcentrates, only 1 transfusion was needed after the dose 4 g/m2. Collection of CD34+ cells started in leukocyte level over 3.5 x 10(9)/l on mobilization day 12-20 (median day 15). The day of the first leukocytapheresis did not depend on the day of the first introduction of G-CSF. Duration of G-CSF administration was significantly shorter in the start of its use after leukocyte count decrease under 1.0 x 10(9)/l. Conduction of 1 to S (median 2) leukocytapheresis was needed for collection of BHSC. Sufficient for 2 autotransplantations number of BHSC were stored in 90 of 93 patients. Cyclophosphamide administration in a dose 6 g/m2 allowed collection of cells sufficient for one autotransplantation for the first leukapheresis in 52 (88.1) patients. A total number of CD34+ cells over 4 x 10(6) cells/kg were collected in 56 (94.9%) patients. In administration of cyclophosphamide in a dose 4 g/m2 mobilization was effective in all 34 patients. The first leukapheresis provided sufficient for one autotransplantation number of cells in 29 (85.3%) patients. CONCLUSION: Administration of high cyclophosphamide doses in combination with G-CSF is an effective and safe method of BHSC mobilization providing collection of adequate number of CD34+ cells for double autotransplantation in 96.8% patients. Cost effective is the start of G-CSF administration in the fall of leukocytes under 1.0 x 10(9)/l. Cyclophosphamide dose 4 g/m2 provides collection of CD34+ cells number sufficient for two autotransplantations in moderate thrombocytopenia and in less number of substitute transfusions in the absence of serious toxic complications.